1993; Kawaguchi et al. 1994; Imbert et al. 1996; Pulst et al. 1996; Sanpei et al. 1996; David et al. 1997; Zhuchenko et al. 1997; Nakamura et al. 2001). Together they account for more than half of all SCA cases, with SCA3 being the most common (Ruano et al. 2014). Subsequently, non‐coding CAG repeats (Holmes et al. 1999; Koob et al. 1999), non‐CAG repeat expansions (Matsuura et al. 2000; Sato et al. 2009; Kobayashi et al. 2011) and, more recently, conventional mutations have been found to underlie different SCA subtypes (Table 1). Here, ATXN3 is linked to autosomal dominant cerebellar ataxia.